Field of the Disclosure
The present invention relates generally to power supplies, and in particular but not exclusively, relates to a new topology and control of switched mode power supplies.
Background
Switch mode power supplies are used in a wide variety of household or industrial appliances that require a regulated direct current (dc) voltage for their operation. There are a wide variety of known ac-dc (off-line) converter topologies for regulating an output quantity of power supply (voltage or current) by using control methods such as PWM (pulse width modulation), PFM (pulse frequency modulation), or on-off control/pulse skipping.
To interface with low frequency (e.g. 60 or 50 Hz) alternating current (ac) networks, an ac-dc front stage converter is often included to provide an efficient power exchange with the ac network as well as function as a power factor correction (PFC) converter at the interface to the ac network.
The two-stage converters are usually advantageous and utilized with a front-stage PFC Boost (as a power factor correction interface with the ac network) that is cascaded with a dc-dc converter (as a step-down voltage regulator). The front-stage PFC Boost receives a rectified ac sinusoidal waveform through a bridge rectifier and is implemented with a high frequency (HF) switching of a power switch to transfer energy through an inductive energy transfer element to the second stage of dc-dc converter.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.